Extreme slow write performance on Sandisk Ultra Plus


I just installed my new SanDisk SSD (Sandisk SDSSDHP-256G-G25 Ultra Plus). But I get extremely slow write speeds (see Screenshot).

I disabled the write cache on my system in order to see the “real” speeds. I’m using Windows 8.1 Pro, AHCI is enabled.

Any suggestions?


I get these results, if I enable the write cache. Write speed is quite bad, too.

Check your partition alignment.

Thanks for your answer. The alignment is set correctly.

Still waiting for help…

speed looks quite a bit better with wite cache enabled. What SATA chipset are you using? Can you benchmark using crystal disk mark and post the results as well?